1. Technical Field
The invention relates to test probes, particularly to retractable test probes.
2. Related Art
A multimeter or a multitester, also known as a VOM (Volt-Ohm meter), is an electronic measuring instrument that combines several measurement functions in one unit. A typical multimeter may include features such as the ability to measure voltage, current and resistance. A multimeter can be a hand-held device useful for basic fault finding and field service work or a bench instrument which can measure to a very high degree of accuracy. They can be used to troubleshoot electrical problems in a wide array of industrial and household devices such as electronic equipment, motor controls, domestic appliances, power supplies, and wiring systems. In some circumstances, test probes of a multimeter must be introduced into narrow gaps to touch the objects to be measured. However, length of current probes is not long enough, so those probes still cannot reach the objects to be measured when they are introduced into gaps.
A typical probe includes a needle and a main sleeve. The needle is rooted in the main sleeve and has a test portion which is protrudent from the main sleeve. Thus the test portion can be used to touch an object to be measured.
However, if the gap which is introduced by the probe is too deep, then the needle cannot touch the object to be measured.